This invention relates generally to hypodermic needles which are adapted to inject substances into humans and animals and/or to withdraw specimens therefrom. More particularly, the present invention relates generally to protective devices which are employed for shielding the needle of a hypodermic syringe or other injecting or withdrawing device.
The vast majority of hypodermic needles are disposable-type needles which are discarded after use. The shielding of the sharp end of the hypodermic needle is of critical concern to health practitioners both in relation to needle disposal and to handling the needle. Accidental exposure to the sharp end of the needle can have very serious and even fatal health consequences. For example, the needle may be contaminated with diseases such as hepatitis and A.I.D.S. It is well documented that accidental puncture with a contaminated needle could result in infection with such diseases. Because the hypodermic needle is frequently used during times of emergency or high stress, it is highly desirable that the needle be immediately shielded after usage in a reliable and efficient manner which provides a high degree of protection from accidental puncture.
A variety of different types of devices for shielding a hypodermic needle against inadvertent needle exposure have been advanced. A number of shield devices involve a sleeve-like member for enclosing the sharp end of the needle. Mitchell U.S. Pat. No. 4,631,057 discloses a shielded needle wherein a needle guard is mounted on the body of the hypodermic syringe. The needle guard moves from a retracted position in which the guard does not shield the needle to an extended position in which the guard shields the needle. The needle guard can be locked in the extended position by interlocking members carried by the needle guard and a collar which is mounted on the body of the syringe.
Sampson et al U.S. Pat. No. 4,573,976 discloses a shielded needle wherein a needle guard is mounted on the body of the syringe. In an extended position, the needle guard obstructs access to the point of the needle. In a retracted position, the guard does not obstruct access to the point of the needle. The guard may be releasably retained in the retracted position. Interlocking members on the syringe body and the guard are responsive to generally axial movement of the guard to the extended position to prevent reverse movement of the guard toward the retracted position.